/Engine/Source/Editor/GraphEditor/Public/SNodePanel.h
Lets the CanvasPanel know that the user is interacting with a node.
virtual void OnBeginNodeInteraction ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SNode](API\Editor\GraphEditor\SNodePanel\SNode) > & InNodeToDrag, const FVector2D & GrabOffset )